In motor vehicle technology, “brake-by-wire” brake systems are becoming increasingly widespread. Such brake systems often has not only a master brake cylinder which can be activated by the vehicle driver but also an electrically controllable pressure supplying device by means of which the wheel brakes or the master brake cylinder are activated in the “brake-by-wire” operating mode. In order to give the vehicle driver a pleasant pedal sensation in the “brake-by-wire” operating mode, the brake systems usually includes a brake pedal sensation-simulating device. In these brake systems, the wheel brake can be activated on the basis of electronic signals even without active intervention by the vehicle driver. These electronic signals can be output, for example, by an electronic stability program or an adaptive cruise control system.
International Patent Application WO 2011/029812 A1 discloses a “brake-by-wire” brake system having a pressure supplying device having a hydraulic cylinder-piston arrangement, one piston of which can be activated by an electric motor with the intermediate connection of a rotational-translational transmission. The pressure supplying device is connected hydraulically to a pressure modulation unit which has one inlet valve and outlet valve per wheel brake. The brake system has a pressure sensor for measuring the generated pressure (brake system pressure) of the pressure supplying device. In the above-referenced application, there are no further details on how setting or adjustment of a predefined setpoint value is to be carried out for the pressure of the pressure supplying device. In particular, there is no mention of how a set brake pressure is checked if the pressure sensor fails.
The object of the present invention is therefore to make available a brake system and a method for operating a brake system having an electrically controllable pressure supplying device which has a cylinder-piston arrangement with a hydraulic pressure chamber, the piston of which can be activated by an electromechanical actuator in order to generate a pressure in the pressure chamber, which permits reliable and correct setting of a desired pressure. This object is achieved according to the invention by means of a method and a brake system according to the description of the present invention.